The number of semiconductor devices to be mounted on an automobile is yearly increasing. Along with the increase, each of the semiconductor devices is required to have high safety. A means to improve safety is a self-diagnosis function of the semiconductor device, for example. The self-diagnosis function can be categorized into a regular diagnosis in which a diagnosis is performed periodically during the operation and an initial diagnosis in which a diagnosis is performed only when the power is turned on. In the initial diagnosis, a diagnosis that requires time in a diagnosing operation and that is hard to be performed at the same time as the normal operation is performed in usual cases.
PTL 1 describes a configuration of a game machine that regularly diagnoses power abnormality at the time of a power failure or the like with use of a power failure detecting circuit and a backup power supply provided externally.